Method of marking film



April 15, 1958 F. J. MAGUIRE METHOD OF1 MARKING FILM Filed July 14, 1953 /NI/IeA/'o/P.

FRANCIS J. MAGUIRE TTORNEY United States listeni- METHD F MARKEN@ FEM Francis Zi. Maguire, Weymouth, Mass., assigner to Tracerlab, line., Boston, Mass., a corporation of Massachuseits Application July 14, 1953, Serial No. 368,615

S Claims. (Cl. 25d-67) rfhis invention relates to a method for marking photographic film and in particular to an improved method for the simultaneous marking of the wrapper and film of a nlm packet of the type used in a hlm badge radiation dosimeter.

ln working with radioactive material operating personnel are often continuously subjected to various types of radiant energy emanating from such materials. In order adequately to safeguard the health of persons Working with or in the vincinity of radioactive materials, it is important that means lbe available for determining the amount, and also the intensity, of exposure to such radiation. One type of dosimeter which has come into widespread use for this purpose is described in Patent No. 2,483,991 and consists of a film holder of special design which employs multiple X-ray films as the radiation sensitive element with which graduated filters are used to provide an indication of the intensity and amount of energy striking the badge. The badge is worn on the clothing of the operator for a predetermined period, for example a week, and the film then developed and examined with a densitometer to measure the dosage to which the wearer has been exposed during the period.

Since the number of people employed in any particular installation where a radiation hazard exists is usually so small as to make the processing and reading of badges of this type prohibitively expensive, service organizations have been established to provide the film badge service on a subscription basis. ln the performance of the service, an unexposed film badge is sent to the customer, is

issuedv by the customer to a particular person, and after a designated period of use is returned to the service company for processing and a determination of the exposure to which the film has been exposed, and a report sent to t'ne customer. Since the badge is a personnel protection device, it follows that each badge and the film contained therein must be positively identified with the user tov/hom it is issued. Various methods have been proposed to accomplish this function, the one suggested in the above-mentioned patent consisting of a filter plate provided with punched out numerals or other marking indicia. The area of the film beneath this cutout section will show increased blackening upon exposure to radiation while on the person of the user, or if desired, that area may be exposed to X-ray or gamma radiation prior to the issuance of the badge. Marking of the film in this way is rather time consuming, however, and the amount of information which can be placed on the film rather limited. Moreover, this type of marking identithe film only and the outside of' the film packet must separately marked with the same data. The ne essity two separate operations in the marking procedure introduces the possibility of error, and obviously is relatively expensive- -..iother method of marking a film which has been adopted by film companies, consists in making an in pression in the emulsion of the film with a stylus or press, and upon subsequent development of the film, the imfilm emulsion by a stylus or other pression develops somewhat darker than the remainder of the film. In the past, the impression has been' made with a die formed with a number of dots arrangedr to outline a number or other indicia. In order that the film not be pierced by the marking operation, the dot producing characters on the die must be rather blunt, thus requiring rather wide spacing, with the result that only large numerals can be made satisfactorily, thus limiting the amount of information that can be put in a given area. inasmuch as the film packet used in the lconventional film badge is only 1% x lf3/4., with only about half of it allotted for identification purposes, ythis method has been shown to b e wholly unacceptable for the identification of film badges.

With an appreciation of the foregoing shortcomingsy of prior art methods of marking film, and particularly the film packets offilm badges, applicantV has asa primary object of. the present invention to provide a method for simultaneously"marking the film and the wrapperk of a film packet.

Another object of the invention isto provide a method for marking` a film packetl andthe film `therein enclosed so as completely to eliminate the possibility of error between the data marked on the two'parts.

A still further object of the invention is toyprovide a fast andinexpensive method of positiyely-identifying the wrapper and enclosed Afilm of afilm packet of the type used in a filmk badge with the kuser ofthe badge.

Further objects of the invention `will.become apparent as the description thereof proceeds with 'reference` to the accompanying drawing, the single figure of which is a generally perspective view, partly` insection, of a film packet.

` TheY film packet used in the film badge is identical, except for the sensitivity ofthe film,l with that usedfor dental X-ray purposes. In order that the device be sensitive over a rather wide range of exposures, the unit comprises two or more sheets of X-ray sensitive filmll and 12 contained in a suitable light-proof wrapping, usually a double thickness of paper, such as 13 and 16. The two or more films are coextensiyeV and are positioned one on top of they other with the emulsion sides i4 and 15 of both facing the front of the packet. One of the. films, preferably the one nearest the`v front of .the packet, namely film l1, is of relatively high sensitivity, such that maximumblackening or" the lm will occur at the end of a` period of exposure integrating about 3 roentgens. Such a film will permit quantitative readings down to about .G5 roentgen. The` other film 12, which is of less sensitivity, should reach maximum blackening with an exposure of about 3G rcentgens. ing of this lrnv is substantially less than the maximum measurable density for the `more sensitive film, hence accurate quantitativeA readings over the complete range can be obtained.

The outer wrapper 16 is preferably white in color, and as was previously mentioned about one-half of the packet area, about 3/t X 1%. is used for identification purposes, with the remainder utilized to measure radiationdosagc. For convenience in mailing and distributing the badges, and upon return, in processing thev film and reporting the results, it is desirable to identify the subscriber, usually by code number, the individual using the badge, usually by name, the date on which use of the badge begins, the type of film used in the packet, and in certain cases, the postal zone to which the badges are to be sent, the foregoing information to appear on both the wrapper t6 and the films 11 and 12. The described prior art methods are clearly unacceptable for accomplishing this function. Applicant has discovered that if the packet is exposed to X-rays or other radiation following the impression of theA meansfor transferring The minimum measurable blacken- 3 the indicia to the film emulsion, and the film then developed, the area subjected to pressure, while developed to some extent, is light in contrast to the remainder of the film. Advantage is taken of this discovery to provide a fast and fool-proof method for marking lm packets of the character described above. The film packet, as received from the film manufacturer, is placed in an Addressograph, or comparable machine, for which plates bearing the desired identifying information have been previously prepared. For example, a file of Addressograph plates is made for each individual subscribing to the service and includes such data as company name, users name, postal zone, etc. The packets are fed into the Addressograph either manually or by an automatic feed mechanism, and the machine, through the action of the printing plate on an inked ribbon, prints the information in ink on the outer wrapper. The normal pressure applied by the platen of the machine is sufficient to cause a corresponding impression to be made on the emulsion of the film nearest the printing plate, and to a limited extent on the second film 14. After being thus printed, that portion of the film allotted for iden- .ticatiom is exposed to penetrative radiation, preferably X-rays, care being taken to shield the remaining portion of the hlm. The packet is then assembled in its cassette (not shown) and sent to the subscriber who distributes them to his personnel in accordance with the names appearing on the front of the badge. After the film is worn for the prescribed period, it is returned for processing, a determination of the exposure, and thesubmission of a report to the subscriber. The processing consists in removing the paper wrapping 13 and 16 from the film, developing the film by standard procedures, and determining exposure by densitometer methods. Since the present invention is concerned only with identification of the packet and film, it is believed unnecessary to discuss the manner in which radiation dosage is determined and reported. lt is significant to note, however, that prior to development of the film, the wrapper is removed and destroyed and only the marking on the film itself is thereafter used to identify the film with the user. In accordance with the present invention, the same infomation as appears in printed form on the wrapper appears on the film with sutcient clarity and reliability as to be completely foolproof. Upon development, the impression made by the printing plate appears as a light image on a darker background, and is easily readable.

Because of the thickness of the paper wrapper and the base of the lm, the impression made on the second less sensitive film may not be sufficiently deep to insure reliable reproduction of the identifying data. To insure that the two films of a particular badge are kept and reported together, a dot code is included on the Addressograph plate, along with the other information previously referred to, and by virtue of the concentrated pressure afforded by the point contact of the dots, the code is impressed reliably on the second film. Thus, after the films are developed, the dot code appears on both films, and by a simple over-lay matching procedure, the two films corresponding to a single film badge can be easily and positively identified.

From the foregoing it is seen that there is provided a simple, inexpensive and foolproof method of simultaneously marking with identifying information, the wrapper and the film, of a hlm packet of the type used in a film badge. It will be readily appreciated, however, that the method may also have applicability in the marking of films used for other purposes without departing from the spirit of the invention. For example, other types of wrapped sheet films may be marked by following exactly the described method, or unwrapped film can be marked by making an impression on the emulsion and exposing it to radiation in the absence of light. It is intended also that the invention should not be limited to marking the wrapper and making an impression with an Addressegraph machine, but includes the marking with a sharp pen, a hand stamp, or other device capable of making a legible marking on the wrapper and a corresponding impression on the film emulsion. A typewriter provided with a suitable holder for the film packet could, for example, be used simultaneously to mark the wrapper and enclosed film. The features of the invention which are believed to be new are particularly pointed out in the appended claims.

What is claimed is:

i. A method of marking a photographic film enclosed in a wrapper opaque to normal light whereby upon development said film may be distinguished from others comprising the steps of making an impression of a distinguishing indicia on the film emulsion through the application of pressure on said Wrapper and thereafter uniformly exposing the portion of the enclosed lm bearing said indicia to radiation penetrative of said wrapper.

2. A method of marking the wrapper and enclosed film of a film packet with identical indicia comprising the steps of making legible distinguishing markings on said wrapper with an attendant application of pressure sufficient to make an impression of said markings on the lm emulsion, and thereafter uniformly exposing the portion of the packet bearing said markings to radiation penetrative of said wrapper, the said impression, upon development of said film appearing as a light image on a dark background.

3. A method of simultaneously marking with identifying information a film and a light-opaque wrapper in which the film is enclosed, comprising the steps of printing the information on the wrapper with sufhcient pressure to disturb the emulsion of the film, and uniformly exposing the portion of the film bearing said information to radiation penetrative of said wrapper, whereby upon subsequent development of said film information corresponding to the printed information on said wrapper appears on said film.

4. A method of simultaneuosly marking with legible distinguishing information a photographic film and a light opaque wrapper in which the film is enclosed, comprising the steps of printing the information with ink on the wrapper with a device utilizing a die and the application of pressure, the applied pressure of the printing operation being sufficient to disturb the emulsion of the film, and thereafter uniformly exposing the portion of the wrapper and film bearing said information to radiation penetrative of said wrapper, whereby upon subsequent development of said film information corresponding to that printed on said wrapper also appears on said film.

5. A method of positively identifying the wrapper and the film of a film packet of the type used in a film badge dosimeter with the user of the badge comprising the steps of printing on the wrapper in ink information identifying the user with a device utilizing a pressure-operated die which simultaneously forms an impression on the emulsion of said film corresponding to said printed information, and Ithereafter uniformly exposing the portion of said packet bearing said information to radiation penetrative of said wrapper, the information printed on said Wrapper positively identifying the badge with the user, and said impression, upon subsequent development of the film, appearing as a light image on a dark background positively identifying the film with the user.

6. A method of marking the film packet of a film badge dosimeter `to provide positive identification of the user on both the outside of the film packet and on the film emulsion, comprising the steps of printing in ink on a portion of the outer side of the film packet adjacent the emulsion side of the film data identifying the user with a device utilizing a pressure-operated die which simultaneously form an impression of said data on the film emulsion, and exposing said portion of the film packet to X-rays or other radiation penetrative of said packet while shielding the remainder, the said impression, upon subsequent development appearing as a light image on a dark background.

7. A method of positively identifying the wrapper and the lm of a lm packet of the type used in a lm badge radiation dosimeter with the user of the badge comprising the steps of printing in ink, with a device utilizing a pressure-operated die on a portion of said wrapper,`data identifying the user, the pressure applied during said printing step causing 'an impression of said data to be made on the emulsion of said lm, and thereafter uniformly exposing the data bearing portion o'f said packet to X-rays, the printed data on said wrapper identifying the badge with the user, and said impression, upon subsequent development of the lm, appearing as a light image of said data on a dark background thereby identifying the fil-m with the user.

8. A method of identifying the light-tight wrapper and the lrn of an assembled lm packet of the type used in film badge radiation dosimeters with the user of the badge comprising the steps, prior to issuance to the user, of printing on a portion of the wrapper in ink data idenu'- fying the user with a device utilizing a pressure-operated die with application of suicient pressure that the die forms an impression of the data on the emulsion of a corresponding portion of said lm, and uniformly exposing said portion of the film packet to X-rays to insure that said portion of the film is dark upon subsequent development of the film, the said data appearing as a. legible contrasting image thereby identifying the lm with the user.

References Cited in the tile of this patent UNITED STATES PATENTS 1,649,621 Slocum Nov. 15, 1927 1,748,490 Martin Feb. 25, 1930 2,257,933 Belknap Oct. 7, 1941 2,630,534 Heinecke et a1. Mar. 3, 1953 2,649,547 Lott Aug. 18, 1953 

